This invention relates to a latching mechanism for a passenger vehicle safety restraint including pretensioning means for pretensioning of a seat belt by means of a crash sensitive pretensioner device.
Vehicle passenger safety restraints most commonly comprise a safety belt which comprises an anchorage or automatic locking webbing retractor on one side of the respective seat from which webbing passes via a shoulder height fitting and diagonally across the occupant to a buckling tongue which is engageable with a buckle anchorage at the other side of the seat. Usually such webbing returns from the buckling tongue as a lap webbing to a floor anchorage on the first side of the seat. Although such a restraint is usually self-tightening by virtue of a retractor and the retractor locks, in the event of specified lower webbing sensing or vehicle sensing `g` values, it is desirable to provide separate means for independently tightening the webbing in impending crash conditions and it has been proposed to provide a pretensioning device in the buckle anchorage.
In automotive vehicles, more especially certain passenger cars, it has been proposed to at least partially integrate the mechanism of mandatory seat belts, especially for movable front seats, into the structures of the seats themselves. While the structure of a seat, especially the mountings and the seat back, need to be more strongly built than in arrangements where webbing retractors and mountings are located on the vehicle door pillars (B-posts), an integrated belt arrangement can provide enhanced convenience for the user and less obstruction of passenger access to rear seats.
Arrangements for integrating a seat belt into a vehicle seat have previously been proposed and it may be noted that when a crash sensitive belt pretensioner is included, it is desirable that the sensing and activating mechanism thereof shall be mounted not on the seat but on the vehicle body, so that manual seat adjustments will not result in activation thereof.
One form of crash-anticipating belt pretensioner is described in European Patent Application No. 88308075.6. In order to use such a pretensioner in connection with a seat belt arrangement which is integrated into a seat structure it is desirable that the pretensioner shall be conveniently located on the vehicle body and connected via a bowden cable to respective movable seat belt anchorage, typically a buckle carried by the movable seat structure. In that case it is desirable to provide means whereby while the bowden cable is required to transmit pretensioning shortening movement to such buckle, neither the pretensioner nor the bowden cable is required to support the full `g` forces created by weight transfer of an occupant during a crash.
It is an object of the present invention to provide a simple and robust pretension latching mechanism for a safety restraint.
According to the present invention there is provided a pretension latching mechanism comprising a first member guidingly carrying a second member for movement over a range of latching positions relative to the first member, one said member having a succession of abutments and the other said member having a latching abutment lockingly engageable with said succession of abutments, one said member having connecting means for connection to a safety restraint and connection means for connection to pretensioning means operation of which acts on said one member to move it relative to the other member to a position in which it tensions the restraint and so that subsequent tension in the restraint is reacted by engagement of said latching abutment with one of said succession of abutments.
In a safety restraint system in which the pretensioning means is located separately from the respective restraint anchorage, the connection means for connection to the pretensioning means may comprise a means for a flexible connection such as a bowden cable. In such a case the anchorage may be mounted to be adjustable with the frame of a respective seat whereas the sensitive pretensioner itself may be mounted directly on the vehicle body so as to be not sensitive to seat adjustment movements. Alternatively, if the respective anchorage is to be attached to the vehicle body, the pretensioning means, which may comprise a compressed spring, can be included in one assembly with the latching mechanism.
Said succession of abutments can be provided by recesses of the first member and the first abutment is a movable detent provided on the locking member.
In one example said second member may comprise a slider on which said abutment member is pivotally mounted, said slider carrying said means for connection via a flexible connection to the pretensioner. In such an example said abutment member may carry attachment means for the restraint tension and said restraint being attached at a point in relation to the pivotal mounting such that it tends to urge said detent into engagement with a recess of said mounting member and said slider may carry spring means urging said detent against said surface.
In another example the second member may itself be tiltably guidingly carried by the first member and have attachment means for the restraint tension such that tension therein tends to urge the respective abutment thereof into engagement with the succession of abutments of the first member.
In another example the latching abutment may comprise a plate-like element carried by the second member and spring loaded towards said first member to be engageable with the succession of abutments thereof.
In order that the invention be more clearly understood and readily carried into effect, the same will be further described by way of example with reference to the accompanying drawings of which